Prof. Celli explores theoretical surface science using analytical and computational methods to study a variety of surface phenomena, and in particular the following:

Atomic and molecular beams are widely used to study the structure and dynamics of solid surfaces on the atomic scale. The energy and distribution of the scattered atoms, when suitably analyzed, reveal a wealth of data on surface morphology and on the motions of surface atoms. Prof. Celli´s work provides the conceptual framework and the practical tools for data analysis, through computer simulations of the atom-surface scattering process and the mathematical modeling of surface phenomena.

Rough surfaces display a significant enhancement of scattering in the backward direction. This effect is commonly seen when shining headlights on highway signs, and also accounts for the enhanced brightness of the full moon. It arises from two causes: geometrical effects that can be understood from simple ray tracing, and coherent wave interference in the backward direction. The two effects can be distinguished by their dependence on angle, polarization, and type of surface roughness. Right now, Prof. Celli is particularly interested in the shape of the coherent peak, because it is related to general questions in quantum theory about the nature of the wave function in non-simple systems.